1. Field of the Invention
The present invention relates to technology that can support a Downloadable Conditional Access System (DCAS) host when the DCAS host moves between networks of an authentication proxy server in a DCAS network. This work was supported by the IT R&D program of MIC/IITA. [2007-S-007-01, The Development of Downloadable Conditional Access System]
2. Description of Related Art
A conditional access system in a cable network determines whether to permit a service based on a user authentication and thereby controls only an authenticated user to view a particular program when a user desires to view the program.
In the case of early conditional access systems, each manufacturer used a different standard and thus each conditional access system was compatible with only equipment produced by a particular manufacturer. Accordingly, since a broadcasting service provider should directly supply an access terminal to a subscriber, the broadcasting service provider had some burdens and had difficulty in updating the conditional access system.
In order to solve the above problems, OpenCable of North America published a standard to separate a conditional access module from a subscriber terminal. This was to prevent a particular CAS provider from monopolizing the market and encourage competition between CAS providers and thereby reduce product price. The conditional access module separated from the subscriber terminal has been standardized as a cable card in a Personal Computer Memory Card International Association (PCMCIA) card type. Accordingly, the broadcasting service provider was able to supply only the cable card to the subscriber without lending the access terminal to the subscriber and thereby provide a paid broadcasting service. However, the price of the cable card and management cost was increased and a terminal retail market was not stimulated, which resulted in debasing the result desired by OpenCable.
In this situation, there emerged technology associated with Downloadable Conditional Access System (DCAS) that can download conditional access software to a subscriber terminal to enable a paid broadcasting service, without needing a separate hardware-based conditional access module.
A DCAS headend system accesses a corresponding network to download conditional access software to an authenticated receiver and the receiver installs the downloaded software. In this instance, a user may receive program access entitlement information that is provided from a conditional access system (CAS) server using the installed software and thereby can view a program.
When the receiver moves to a network of another authentication proxy server and then initially accesses the network of the other authentication proxy server, no mechanism is specified to continue to provide the receiver with program access entitlement information corresponding to the network of the previously accessed authentication proxy server from the network of the newly accessed authentication proxy server. In this case, even though the user moves to the authentication proxy server network of the same cable service provider, the user may not view the program.
Also, although a corresponding receiver no longer exists in the network of the previous authentication proxy server, program access entitlement information is continuously transmitted to the previous network. Accordingly, communication resources may be wasted and the usage efficiency of the network may be deteriorated.
Accordingly, there is a need for technology that can more effectively support the mobility of a DCAS host.